1. Field of the Invention
Non-phosphorus oligomeric biodegradable builders for detergent compositions.
2. Description of the Prior Art
In recent years the problem of eutrophication, which can be defined as a slow rate, natural process of enrichment of waters with nutrients, such as phosphorus and nitrogen has received much notoriety. Uncontrolled or pronounced eutrophication has been found to cause increased algal growth and agal scums which not only are unaesthetic, odorous, distasteful and clog filters or treatment plants but also creates disproportionate demands on the available oxygen in the water. It has been postulated that in several bodies of water various human activities have contributed to acceleration of the process through such factors as inordinate enrichment of natural runoff, ground water and agricultural drainage, sewage and waste effluents. It has also been suggested that the phosphorus-containing builders present in detergent compositions can be a contributing factor in eutrophication, and therefore any substitutes which do not contain phosphorus may decrease to some extent the eutrophication problem. Thus, those skilled in the art have expended a great deal of time and money to solve this problem and find suitable materials to reduce or replace the existing phosphate builders in detergent compositions. This work is still continuing since most of the builders discovered to date have been deemed unsatisfactory for a variety of reasons and are most often less efficient than the existing phosphate builders.
High molecular weight acrylate polymers have been known in the art for many years, finding significant use as molding resins, films and fibers. Particular species of the higher molecular weight acrylate polymers, such as sodium polyacrylates in British Pat. No. 1,090,809 and alpha halogen substituted polyacrylates such as polyalpha chloracrylic acid, polyalpha fluoracrylic acid and copolymers thereof with other polymerizable organic compounds, in U.S. Pat. No. 2,327,302 have been suggested as capable of functioning as detergent assistants. These compounds, however, create as much, if not more, of a problem than they ostensibly solve since at the molecular weight of the polymers believed contemplated by these patents, the molecules could not be biodegradable.
A large proportion of the sanitary treatment performed in this country is done aerobically. If the bacteria in the degradation system cannot consume and degrade a molecule it may pass through the tank and flow into the surrounding area, ultimately mixing with the surface water and eventually becoming part of the human water supply. It has been found that, bacteria either cannot or have extreme difficulty in degrading long chain polymers and branched polymers of the type disclosed in the above patents. Since so little is known about the effects of so many chemicals, particularly from a carcinogenic and birth defects standpoint, when ingested by human beings, a compound intended for use in a detergent formulation must be biodegradable or it is dropped from further consideration. As such, the compounds of British Pat. No. 1,090,809 and of U.S. Pat. No. 2,327,302, as well as other relatively high molecular weight polyacrylates would be deemed unacceptable for use in a detergent formulation.